2.3.2 Running an Application in a Pod

The software described in this documentation is either no longer supported or is in extended support.
Oracle recommends that you upgrade to a current supported release.

2.3.2 Running an Application in a Pod

To create a pod with a single running container, you can use the kubectl create command:

$ kubectl create deployment --image nginx hello-world
deployment.apps/hello-world created

Substitute hello-world with a name for your deployment. Your pods are named by using the deployment name as a prefix. Substitute nginx with a container image.

Tip

Deployment, pod and service names conform to a requirement to match a DNS-1123 label. These must consist of lower case alphanumeric characters or -, and must start and end with an alphanumeric character. The regular expression that is used to validate names is '[a-z0-9]([-a-z0-9]*[a-z0-9])?'. If you use a name for your deployment that does not validate, an error is returned.

There are many additional optional parameters that can be used when you run a new application within Kubernetes. For instance, at run time, you can specify how many replica pods should be started, or you might apply a label to the deployment to make it easier to identify pod components. To see a full list of options available to you, run kubectl run --help.

To check that your new application deployment has created one or more pods, use the kubectl get pods command:

$ kubectl get pods
NAME                           READY     STATUS    RESTARTS   AGE
hello-world-5f55779987-wd857   1/1       Running   0          1m

Use kubectl describe to show a more detailed view of your pods, including which containers are running and what image they are based on, as well as which node is currently hosting the pod:

$ kubectl describe pods
Name:               hello-world-5f55779987-wd857
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               worker1.example.com/192.0.2.11
Start Time:         Fri, 16 Aug 2019 08:48:33 +0100
Labels:             app=hello-world
                    pod-template-hash=5f55779987
Annotations:        <none>
Status:             Running
IP:                 10.244.1.3
Controlled By:      ReplicaSet/hello-world-5f55779987
Containers:
  nginx:
    Container ID:   cri-o://417b4b59f7005eb4b1754a1627e01f957e931c0cf24f1780cd94fa9949be1d31
    Image:          nginx
    Image ID:       docker-pullable://nginx@sha256:5d32f60db294b5deb55d078cd4feb410ad88e6fe7...
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Mon, 10 Dec 2018 08:25:25 -0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-s8wj4 (ro)
Conditions:
  Type              Status   
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-s8wj4:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-s8wj4
    Optional:    false
QoS Class:       BestEffort  
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
....